(1) Field of Invention:
This invention relates to latches or fasteners for containers. Particularly it relates to means for permanently securing lids of box type containers used for the storage of low level nuclear waste.
(2) Description of Prior Art:
The storage of low level nuclear waste poses container problems not faced by the storage of conventional materials. Safety in handling and in storage constitute paramount considerations. Locking devices are usually for one-time use and must provide an air tight seal between the lid and the box to obviate any leakage.
Fasteners for boxes found in the early art would not meet the needs of nuclear storage. The invention of Andrus (1899) used the technique of folding a pliable retainer wire, attached to the box, through and over a loop attached to the lid. Permanent, air tight sealing was obviously not a consideration. Also, the wire members were of light construction and designed for repeated openings and closings of the container.
Adjustable locking devices are found in other applications, such as gate latches. Brace (1913) utilized a key stone shaped loop which slipped beneath one of a series of downwardly projecting lips. Permanence was not a factor in its design. The can fastening of Ellis (1921) introduced a tongue which was affixed to the bottom of a container in a position where the tongue automatically entered a keeper affixed to the cover when the container was closed. The upper portion of the tongue was then bent down over the top edge of the keeper to hold the cover in place. No capability for adjustment or air tight sealing were provided. The design might allow a slight downward travel of the cover. Leigh's cover fastener of 1924 is similar to the pliable wires of Andrus but a plurality of the fasteners were distributed about the periphery of the upper portion of the container. The retainer wire could easily be restraightened to permit reentry into the container.
Slidability is first found in the fastening device of Dougherty (1923). A closed loop affixed to the lower part of the container rotated in a bearing and could be raised upward to disengage the loop from the keeper or lug attached to the cover. The loop could then be slid horizontally in the bearing to get the loop out of the way. The loop served only this limited purpose and no adjustability or sealing was provided.
The closure fastener of Marus (1946) again utilized wire loops. The improvement appeared to be that the tongue, affixed to the lower part of the container, was hinged as a separate element and folded up through, and downwardly over, the upper loop on the cover to fasten the container.
Lock-arm closure devices are frequently used on enclosures containing radiation sources. Piggot's Ragiation Projector (1949) utilized a cover handle assembly having two pins which engaged a pair of hooks attached to the bottom of the container. The handle pivoted downward to lock the cover in place. Fold-over locking arms are also found on garbage cans where resilient side walls permit a tight or sealing fit when the pivoted loops on the cover are slipped over a locking arm on the base of the container.
The most recent application of permanent lid holding assemblies for waste containers is found in Teague's patent of 1983. The reverse of the tongue and keeper of Ellis, a flexible angle flange tongue, affixed to the cover, slips downwardly, when closed, into a plurality of metal stirrups and is held therein by a retaining strip on the tongue which springs forward once the tongue is in place. Some flexibility is present in that the tongue, when in place, can move downwards but not upwards. Sealing gaskets were provided between the lid and the box.
As can be concluded from the above observations, the combination of loops and locking arms as locking devices is not new in the art. However, most devices are for continued use and are not permanent in nature. None of the devices had a provision for keeping the ring in an upright position to facilitate loading. Also none of the devices had the strength and safety of the ring and metal retaining strap of the present invention. The flexibility in the design of the present invention also assures a tight seal between the lid and the box when the container is in a closed condition. The design also provides some give in the structure of the latch under a stacking environment.
Prior art known to this inventor includes the following U.S. Pat. Nos.:
624,286, May 1899, Andrus;
1,057,522, Apr. 1913, Brace;
1,383,701, July 1921, Ellis;
1,596,054, Aug. 1926, Leigh;
1,601,352, Sept. 1926, Dougherty;
2,459,666, Jan. 1949, Marus;
2,477,648, Aug. 1949, Piggot et al.;
4,035,009, July 1977, Jacobs;
4,371,092, Feb. 1983, Teague.